DID A SUBMARINE SLIDE TRIGGER THE 1918 PUERTO RICO TSUNAMI?

The 1918 tsunami that inundated northwest Puerto Rico with up to 6 m waves has been attributed to seafloor faulting associated with the 1918 Mona Canyon earthquake. During the earthquake a series of submarine cable breaks occurred directly off the northwest coast of Puerto Rico where the largest tsunami waves came ashore. Here, we use a recently compiled geophysical data set to reveal that a 9 km long landslide headwall exists in the region where cable breaks occurred during the 1918 earthquake. We incorporate our interpretations into a near-field tsunami wave model to evaluate whether the slide may have triggered the observed 1918 tsunami. Our analysis indicates that this slide could generate a tsunami with phase, arrival times, and run-ups similar to observations along the northwest coast of Puerto Rico. We therefore suggest that a submarine slide offers a plausible alternative explanation for generation of this large tsunami.